The 5th generation (5G) mobile network is proposed as the next telecommunications standard beyond the current 4th generation (4G) standard. In particular, 5G-NR is part of a continuous mobile broad evolution process to meet the requirements of 5G. 5G-NR aims to provide better levels of latency, reliability, and security, to enable the connectivity of a massive number of Internet of Things (IoT) devices and other types of mission-critical services.
A major challenge of using millimeter wave (mmWave) for 5G access is to establish a link between a base station and a user equipment (UE) amidst higher path loss and rapidly changing channel conditions between the base station and the UE. At mmWave frequencies, a small variation in the environment can change the condition of a channel and affect receiver performance. Analog beam sweeping and beam tracking techniques are needed in massive multiple input multiple output (MIMO) systems to create highly directed beams that facilitate establishing a proper link between a base station and a UE. Beam steering is needed for initial access where a reliable link is established between a base station and a UE. Once a link is established, a beam tracking technique is required to maintain the link between a base station and a UE. Otherwise, at mmWave frequencies, due to environmental changes, received signal strength may be reduced significantly leading to a disconnection of the link between a base station and a UE.
NR has proposed forming a synchronization (sync) signal block by concatenating a physical broadcast channel (PBCH), a secondary spreading sequence (SSS), and a primary spreading sequence (PSS). While the format of the synchronization signal block has not been determined, different proposals for the arrangement of the synchronization sub-blocks have been suggested.